JPH05341704A - Hologram display device - Google Patents

Abstract

PURPOSE:To enable bright observation of them formed hologram image by condensing a luminous flux forming the reproduced hologram image near to the observer's pupil position by an optical system having a positive power. CONSTITUTION:A reflection diffraction is induced by a hologram plate 1 and the hologram image is reconstructed near the hologram plate 1 in such a manner that the virtual image is visible when viewed from the left side of the hologram plate 1 when the light beams from a reconstructing light source 2 and a projecting lens 3 are projected toward the hologram plate 1 from the left side. Both image planes 1a and 1b have a spherical surface shape and exist apart a prescribed distance. The rectangular images for indicating the visual field of a finder are formed on the image planes 1a and 1b. Since a concave half mirror 4 has the positive power, the luminous flux forming the hologram image reconstructed by the reconstructing light image 2 is condensed near to the observer's pupil 5 position through the concave half mirror 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram display device, and more particularly to a hologram display device suitable for an alvada type finder.

[0002]

2. Description of the Related Art Conventionally, there is known a technique for displaying a field frame of a finder of a camera by a hologram. JP-A-59-185319, JP-A-60-23838, JP-A-60-60627 and the like propose reverse Galileo type viewfinders to which such a technique is applied. On the other hand, the present applicant has proposed a sports finder capable of displaying an accurate visual field by applying the above technology to a plain viewfinder which is said to be difficult to accurately indicate the visual field range (Japanese Patent Laid-Open No. 2- 8
No. 7129).

[0003]

However, the above-mentioned reverse Galilean viewfinder has a problem that the field of view is small and difficult to see. Further, the transparent finder is not yet in a satisfactory state in terms of brightness.

The present invention has been made in view of these points, and an object thereof is to provide a hologram display device capable of displaying a bright hologram image.

[0005]

To achieve the above object, a hologram display device of the present invention comprises a hologram plate on which a hologram image is recorded, a reproducing means for reproducing the hologram image recorded on the hologram plate, and A hologram image recorded on the hologram plate is such that a light beam forming a hologram image reproduced by the reproducing means is near an observer's pupil position through the optical system having the positive power. It is characterized in that it is recorded so as to be focused on.

[0006]

According to this structure, the light beam forming the reproduced hologram image is condensed near the position of the observer's pupil by the optical system having a positive power. It is brighter than the hologram display.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an embodiment of the present invention applied to a finder.

Reference numeral 1 is a hologram plate on which a hologram image is recorded. Reference numeral 2 denotes a reproduction light source including an LED or the like provided as reproduction means for reproducing a hologram image, and emits light of a predetermined wavelength. A light projecting lens 3 is arranged between the hologram plate 1 and the reproduction light source 2. The light projecting lens 3 has a function of condensing the light emitted from the reproduction light source 2. Further, the light projecting lens 3 shortens the arrangement interval between the reproduction light source 2 and the hologram plate 1 to make the viewfinder compact.

The hologram plate 1 is a reflection hologram. As shown in the figure, the reproduction light source 2 and the projection lens 3
When light is radiated from the left side toward the hologram plate 1,
The hologram image is reproduced in the vicinity of the hologram plate 1 so that the hologram plate 1 causes reflection and diffraction so that a virtual image can be seen when viewed from the left side of the hologram plate 1. 1a and 1b are
The image surface of the reproduced hologram image is shown. Image plane 1a
And 1b both have a spherical shape as shown,
Located at a predetermined distance from each other. Then, a rectangular image is formed on each of the image planes 1a and 1b to show the finder field.

The hologram plate 1 is subjected to a half mirror process. This is because the hologram plate 1 is a reflection type hologram as described above, so that it is necessary to reflect the irradiation light and to transmit the light from the subject. It should be noted that if a volume hologram is used for the hologram plate 1, it is possible to realize a structure with high efficiency of reflecting the irradiation light and transmitting the other light without performing the reflection processing.

Reference numeral 4 is a concave half mirror. The concave half mirror 4 has a positive lens power due to reflection on the concave surface side, but has almost no lens power as transmitted light. As described above, since the concave half mirror 4 has a positive power, the light flux forming the hologram image reproduced by the reproduction light source 2 is condensed near the position of the observer's pupil 5 through the concave half mirror 4. .. Since the recording of the hologram image on the hologram plate 1 is performed so that the light flux is condensed as described above, a bright hologram image can be displayed. Other optical systems having a positive power may be used as long as they have such properties.

Next, the function of the finder to which this embodiment is applied will be described with reference to FIG. A photographic subject (not shown) is located on the left side of the concave half mirror 4 in FIG. The light from the subject passes through the concave half mirror 4, further passes through the hologram plate 1, and reaches the pupil 5. Since the concave half mirror 4 and the hologram plate 1 have almost no lens power with respect to the transmitted light, the object is observed with the same size and distance as when viewed without passing through the finder.

The rectangular image reproduced on the image planes 1a and 1b by the reproducing light source 2 and the light projecting lens 3 is reflected by the concave half mirror 4 and then passes through the hologram plate 1 to reach the pupil 5. Due to the positive lens power at the reflection of the concave half mirror 4, the rectangular image forms a virtual image on the far left side from the position of the pupil. This virtual image functions as a visual field frame for indicating the shooting range. Since the image plane 1a and the image plane 1b are separated from each other, each virtual image formed by the concave half mirror 4 is located away from the pupil 5 by a distance different from each other.

In this embodiment, a rectangular image is once formed in the vicinity of the hologram plate 1 without directly forming the visual field frame image by the hologram plate 1, and a virtual image of the visual field frame is formed by the lens power of the concave half mirror 4. Has become. The hologram can theoretically create a stereoscopic image even at a position distant from the hologram. However, in reality, the image is blurred due to the wavelength shift of the light source or the size of the light source. The deterioration of the image becomes more remarkable as the reproduced hologram image is separated from the hologram plate 1 by a larger amount. In this embodiment, since the hologram image is formed near the hologram plate 1, a good image can be obtained.

Further, this hologram image reaches the pupil through the concave half mirror 4, but in order to correct the aberration due to the concave half mirror 4, especially the curvature of field, the image surface 1a is corrected.
The hologram information to be described later is recorded so that 1 and 1b have a spherical shape. The curvature of the hologram image reproduced near the hologram plate 1 is not limited to the spherical shape, and may be an aspherical shape as long as it has a shape that corrects the aberration caused by the concave half mirror 4.

Next, the relationship between the two hologram images on the image planes 1a and 1b will be described with reference to FIG. Generally, when the optical axis of the shooting lens and the optical axis of the viewfinder are different,
Parallax occurs. In other words, the shooting range viewed from the viewfinder changes depending on the subject distance. For example, in FIG. 2, the line 10 drawn from the photographing lens center CT indicates the actual photographing range, but the photographing range viewed from the viewfinder is drawn from the viewfinder center CF when the subject is a long distance. This corresponds to the range between the lines 11 and, when the subject is at a short distance, the range between the lines 12 drawn from the finder center CF.

Therefore, the hologram display device of the present embodiment is configured to simultaneously display a long-distance visual field frame image and a short-distance visual field frame image. Furthermore, to make it easy to distinguish whether they are for long-distance or short-distance, the long-distance field frame is viewed at a long distance through the viewfinder, and the short-distance field frame is viewed at a short distance through the viewfinder. It is configured to form a field frame image in three dimensions. The rectangular hologram image on the image plane 1a in FIG.
A view field frame for short distance is shown by forming a view field image at position 13 in FIG. Similarly, the hologram image on the image plane 1b in FIG. 1 shows a field frame for a long distance by forming a field frame image at the position 14 in FIG.

With the above structure, the long-distance visual field frame and the short-distance visual field frame are observed at the same positions as the long-distance subject and the short-distance subject, respectively. There is no mistake, and the correct shooting range can always be known even in the field of view in which a long-distance subject and a short-distance subject are mixed.

3A and 3B show the hologram plate 1, the hologram images 21 to 24, the reproduction light sources 2a and 2b, and the light projecting lenses 3a and 3b from the position of the concave half mirror 4 in FIG. It is the figure seen. As shown in FIG. 3, the reproduction light source 2 and the projection lens 3 in FIG. 1 are composed of two sets of a reproduction light source 2a and a projection lens 3a, and a reproduction light source 2b and a projection lens 3b. The directions in which each set irradiates the hologram plate 1 are different, and the irradiation directions are separated by 90 degrees or more.

The hologram plate 1 reproduces a hologram image by the reproduction light source 2a and the projection lens 3a, and reproduces the light source 2b.
And a multiple hologram capable of reproducing the hologram image by the light projecting lens 3b. Reproduction light source 2a,
Since the display pattern is switched with the switching of 2b, it is possible to reproduce different images. It should be noted that each pattern of the multiple hologram is configured so that areas where information is recorded on the hologram plate do not overlap each other.

FIG. 3A shows a state in which the reproduction light source 2a is turned on. A rectangular image 21 is reproduced on the image plane 1a (FIG. 1) and a rectangular image 22 is reproduced on the image plane 1b (FIG. 1). To be done. Figure 3 (B) shows
The state where the reproduction light source 2b is turned on is shown, and the image plane 1a is shown.
A rectangular image 23 on (FIG. 1) and a rectangular image 24 on the image plane 1b (FIG. 1)
Is played. Switching between reproduction of the images 21 and 22 (hereinafter referred to as “image IA”) and reproduction of the images 23 and 24 (hereinafter referred to as “image IB”) is performed by changing the focal length of the photographing lens 41 (FIG. 7) described later. It is done in conjunction. By reproducing the image IA when the photographing lens 41 is a wide-angle lens and reproducing the image IB when the photographing lens 41 is a telephoto lens, it is possible to see a field of view that matches the focal length of the photographing lens 41.

Generally, in the multiple hologram, the diffraction efficiency of the hologram becomes poor, but in this embodiment, the multiple hologram does not reduce the diffraction efficiency. This is because the image IA and the image IB formed by switching in the vicinity of the hologram plate 1 have shapes that do not overlap each other, so that the information regarding the image IA recorded on the hologram plate 1 and the information regarding the image IB are This is because they are recorded in different areas without any lag.

FIG. 4 shows the spectral characteristics of the concave half mirror 4.
6 is a graph showing (reflectance and transmittance). In addition, Table 1 below
The thin film structure of the concave half mirror 4 is shown in FIG. As shown in FIG. 4, the emission wavelength of the reproduction light source 2 in the visible range (about 660 nm)
High reflectance is shown only in the vicinity, and high transmittance is shown in other wavelength regions. Therefore, the hologram image IA or IB reproduced by the reproduction light source 2 is the concave half mirror 4
The high reflectance of the object makes it appear bright, and the general light from the subject also looks bright due to the high transmittance of the concave half mirror 4.

In the hologram display device of this embodiment, the pupil position 5 (FIG. 1) for seeing the entire viewfinder field is almost fixed. Therefore, when the eyes are moved greatly from this position, the field of view is eclipsed by the concave half mirror 4. Therefore, in this embodiment, the diffracted light on the hologram plate 1 is directed toward the pupil position 5 as much as possible, thereby making the hologram field of view display bright. With such a configuration, it is preferable that the hologram information is recorded by a method similar to a two-step rainbow hologram when recording the hologram information. Hereinafter, a method of recording hologram information will be described with reference to FIGS.

The first step of the hologram information recording method will be described with reference to FIG. Reference numeral 31 denotes an object having the shape of the hologram image described above (for example, IA in FIG. 3A), which is made of wire or the like. 34 is a lens,
It has the same lens power as the concave half mirror 4.
Reference numeral 35 is a first hologram recording plate. The object 31 and the lens 34 are separated by the same distance as the distance between the hologram plate 1 and the concave half mirror 4. Further, the lens 34 and the first hologram recording plate 35 are separated by the same distance as the distance between the concave half mirror 4 and the pupil 5. In the first step, the object 31 is irradiated with the illumination light 32, the light diffused from the object 31 is guided to the hologram recording plate 35 through the lens 34, and the first reference light 33, which is different from this, interferes with the first reference light 33. The hologram recording is performed.

The second step of the hologram information recording method will be described with reference to FIG. The first step (Fig. 5)
The real image 37 is reproduced at the same position as the object 31 by the first reproduction light 36 without changing the arrangement state of the lens 34 and the first hologram recording plate 35 having hologram information recorded therein. The first reproduction light 36 is the first reference light 33.
Is a conjugate light with the same wavefront as the opposite direction. The second hologram recording is performed on the second hologram recording plate 39 by the interference between this and the second reference light 38. As the second reference light 38, the same light as the light produced by the reproduction light source 2 and the projection lens 3 of FIG. 1 is used. The second hologram recording plate 39 on which hologram information is recorded and the hologram plate 1 have an equivalent relationship.

The method shown in FIGS. 5 and 6 is different from a general rainbow hologram producing method in that a lens 34 equivalent to the concave half mirror 4 is provided between the object 31 and the first hologram recording plate 35. In the rainbow hologram, the first hologram recording plate is long in the horizontal direction,
In the method applied to this embodiment, the point is shortened in the horizontal direction in accordance with the movable area of the pupil 5. The hologram image reproduced by using the second hologram recording plate 39 created by this recording method becomes a light beam which is concentrated on the position where the first hologram recording plate 35 was located through the lens 34. Therefore, when incorporated in the hologram display device of this embodiment, the diffracted light of the hologram is concentrated on the pupil 5 and a bright image is obtained. The method of transferring the second hologram recording plate recorded in the above two steps to a mold to create a replica is a general technique in mass production of holograms.

The hologram plate 1 used in this embodiment is
It is a multiple hologram for displaying fields of view at different focal lengths. Therefore, the two steps of FIG. 5 and FIG.
Repeat twice for the wide-angle lens and the telephoto lens. However, on one second hologram recording plate 39,
The second reference light 38 is emitted from different directions for the wide-angle lens and the telephoto lens. Note that, as described above, since the respective information of the image IA for the wide-angle lens and the image IB for the telephoto lens does not overlap on the hologram plate 1,
When recording each information in the second step of FIG. 6,
By shielding the area having no information on the second hologram recording plate 39, it is possible to secure the diffraction efficiency in the case where the hologram is not multiplexed even if it is a multiplexed hologram.

Lens 34 used in the method of FIGS. 5 and 6.
Has the same power as the concave half mirror 4, but even if the lenses have different powers, the focal length of the lens 34, the first hologram recording plate 35, and the object 3
If the positional relationship with 1 is similar, the diffracted light from the second hologram recording plate 39 is obtained at the same angle. Also, 1
The same hologram can be obtained by applying the step rainbow hologram. In this case, the object and the field of view mask
The lens 34 may be disposed between (the slit shape in the one-step rainbow hologram, which corresponds to the first hologram recording plate in the method for producing the two-step rainbow hologram).

FIG. 7 is a perspective view showing the whole camera equipped with a finder to which this embodiment is applied. Reference numeral 40 is a camera body, 41 is a taking lens, 43 is a release button, and 42 is a focal length switching button which also serves as a main switch. As described above, the focal length switching button 42
Thus, the focal length of the photographing lens 41 is switched, and at the same time, the reproduction light source 2a and the reproduction light source 2b shown in FIG. 3 are switched. The hologram plate 1 and the concave half mirror 4 can be folded into the camera body 40 when not in use by the hinge mechanisms 80a and 80b, respectively. The reproduction light sources 2a and 2b and the light projecting lenses 3a and 3b are inside the camera body, but they are omitted in the figure.

Reference numeral 44 denotes a simple display device which is located on the front surface of the camera body 40 and simply displays at which position in the photographing range the subject is to be seen from the subject side when the self-timer is used. This also uses a hologram and is composed of a hologram plate whose display pattern changes depending on the viewing direction.

FIG. 8 shows a change in display on the simple display device 44. According to the simple display device 44, depending on which direction on the subject side the camera body 40 is viewed, the display can be 44a-4.
It changes like 4i. Reference numeral 45 indicates a shooting range during wide-angle shooting, and 46 indicates a shooting range during telephoto shooting. 45 and 4
6 always looks the same, regardless of the viewing direction of the camera. The position and shape with respect to the displays 45 and 46 change depending on the viewing direction in which the displays 47a to 47i change. The black circles 47d, 47e, and 47f indicate that the shooting range is entered in the telephoto shooting. White circles 47b, 47c, 4
7g and 47h indicate that it is within the photographing range in the wide-angle state. The symbols 47a and 47i of x indicate that the image is out of the photographing range.

The hologram recording method of the simple display device 44 is
This will be described with reference to FIGS. 9 and 10. Simple display device 44
The recording is performed by a method in which a holographic stereogram is combined with a two-step rainbow hologram.

With the configuration shown in FIG. 9, the first step in the two-step rainbow hologram is performed. At this time, the patterns sequentially recorded on the film 51 (44a in FIG.
The same pattern as that of ˜44i) is projected through the lens 52 onto the screen 53. A slit 55 is arranged in front of the first hologram recording plate 54, and the slit 55
Moves horizontally in association with the film 51. The pattern is projected onto the screen 53 by the illumination light 56 from the rear of the film 51, and the light from the screen 53 and the reference light 5
The light of 7 exposes the first hologram recording plate 54 only between the slits 55. The exposure is repeated by sequentially changing the slit 55 and the film 51 to perform full exposure of the first hologram recording plate 54. This method is the same as the recording of the holographic stereogram, but the first hologram recording plate 5 is used.
4 has a shape that is long in the horizontal direction and short in the vertical direction for the next recording step of the rainbow hologram.

With the configuration shown in FIG. 10, the second step in the two-step rainbow hologram is performed. This second step is almost the same as the second step described with reference to FIG. The first reproduction light 58 is conjugate with the first reference light 57 and forms a real image 59. Holographic recording is performed by the second reference light 60 from the direction perpendicular to this.

Simple display device 4 produced by the above method
Since 4 is a rainbow hologram, clear image reproduction is possible even with white light such as sunlight, and a light source for reproduction is not required.

11 and 12 show a structure in which the eaves 95 is foldably provided by the hinge mechanisms 90a and 90b in the camera shown in FIG. Like this eaves 95
11 and by setting the folded state shown in FIG. 11 to the set state shown in FIG. 12, the eaves 95 is applied to the forehead so as to prevent the finder member such as the hologram plate 1 from hitting the eyeglass when the eyeglass is used. You can The eaves 95 also has a function of cutting off ghosts caused by external light.

FIG. 13 shows a structure in which the camera shown in FIG. 7 is provided with a cover 97 for covering the hologram plate 1 and the concave half mirror 4. By providing the cover 97 in this manner, it is possible to prevent contact of eyeglasses at the time of shooting, cut off external light, and the like, as in the configuration shown in FIGS. 11 and 12.

[0039]

[Table 1]

[0040]

As described above, according to the hologram display device of the present invention, the hologram image recorded on the hologram plate is an optical beam whose luminous flux forming the hologram image reproduced by the reproducing means has a positive power. Since it is recorded so as to focus near the observer's pupil position through the system,
A hologram display device capable of displaying a bright hologram image can be realized. A bright finder can be constructed by using the hologram display device of the present invention.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a finder to which an embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining the relationship between two hologram images formed in the finder to which the embodiment of the present invention is applied.

FIG. 3 is a diagram showing a schematic configuration of a finder to which an embodiment of the present invention is applied, viewed from the subject side.

FIG. 4 is a graph showing spectral characteristics of a concave half mirror used in an example of the present invention.

FIG. 5 is a diagram for explaining the first step in the method of recording hologram information on the hologram recording plate for producing the hologram plate used in the embodiment of the present invention.

FIG. 6 is a diagram for explaining a second step in the method of recording hologram information on the hologram recording plate for producing the hologram plate used in the embodiment of the present invention.

FIG. 7 is a perspective view showing the external appearance of a camera equipped with a finder to which an embodiment of the present invention is applied.

FIG. 8 is a diagram showing a change in display on a simple display device of a camera equipped with a finder to which an embodiment of the present invention is applied.

FIG. 9 is a diagram for explaining the first step in the hologram recording method of the simple display device of the camera equipped with the finder to which the embodiment of the present invention is applied.

FIG. 10 is a diagram for explaining the second step in the hologram recording method of the simple display device of the camera equipped with the finder to which the embodiment of the present invention is applied.

FIG. 11 is a perspective view showing an appearance when a visor provided is in a folded state in a camera equipped with a finder to which an embodiment of the present invention is applied.

FIG. 12 is a perspective view showing the external appearance of a camera equipped with a finder to which an embodiment of the present invention is applied, when the eaves provided are in a set state.

FIG. 13 is a perspective view showing the external appearance of a camera equipped with a finder to which an embodiment of the present invention is applied and provided with a cover.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hologram plate 2 ... Reproducing light source 3 ... Projection lens 4 ... Concave half mirror 5 ... Pupil 1a, 1b ... Image plane

Front Page Continuation (72) Inventor Takao Kobayashi 2-3-13 Azuchi-cho, Chuo-ku, Osaka Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Ken Yano 2-3-13 Azuchi-cho, Chuo-ku, Osaka Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Koji Hamaguchi 2-3-3 Azuchi-cho, Chuo-ku, Osaka City Osaka International Building Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A hologram plate on which a hologram image is recorded,
The hologram image recorded on the hologram plate is provided with a reproducing means for reproducing the hologram image recorded on the hologram plate and an optical system having a positive power, and the hologram image recorded on the hologram plate is a light beam forming a hologram image reproduced by the reproducing means. Is recorded so as to be condensed near the position of the observer's pupil through the optical system having the positive power.